fix: fix a symbol name

Author: kkebo

Sources/AsmSupport/aarch64/boot.S

@@ -26,7 +26,7 @@ _start:
     cbnz w2, 3b
 
     // jump to Swift code, should not return
-4:  bl main
+4:  bl Kernel_main
     // for failsafe, halt this core too
     b 1b